With the oilseed rape area expected to increase this autumn, Corteva Agriscience is advising farmers to consider a reactive approach to weed control in order to reduce risks during crop establishment. Charlotte Cunningham reports.

Buoyant prices for the 2021 crop are being underpinned by demand from processors and it’s likely that significantly more OSR will be drilled this August and September compared to the same period last year.  

Early predictions are that the c 280,000ha of crop being harvested now will be comfortably exceeded.  

But with the unpredictable nature of the weather, and the threat of pest damage still present, Corteva is urging farmers to consider strategies which minimise risk. 

“Research has helped improve knowledge around how to successfully establish a resilient crop, and new thinking has developed in the face of pest and weather challenges seen in recent years,” says John Sellars, OSR herbicides manager.

“But OSR growers will still be determined to minimise risk as much as possible, driven by variety choice, drilling dates, targeting soil moisture and an effective herbicide programme.”

One tactic which has proven extremely effective in the UK over the past two seasons is to switch away from a broadacre pre-emergence approach to weed control.  

John believes that Belkar, from Corteva Agriscience, has become an intrinsic part of these integrated strategies.

The post-emergence herbicide deals with key weeds such as poppy, cleavers, shepherd’s purse, fumitory and cranesbill without the need to invest up-front in residual chemistry. 

The Arylex active + picloram formulation allows growers to wait until a crop has established and weeds have germinated before deciding on their herbicide investment. 

Unrelenting demand

“Demand for quality British OSR is unrelenting and the associated gross margins remain unrivalled, still making it the break crop of choice for a huge number of farms,” he adds. 

“However, those who grow it want to employ an establishment strategy that puts less investment up front in the programme, allowing them to see how the crop and weeds are emerging before making their next important decision on inputs. 

“Drilling dates are being altered and pest management plans are being revisited, and the same can be said for herbicides.”  

Belkar paves the way for growers to switch from higher-risk preventative to reactive autumn weed control strategies, believes John.

“Growers can wait until the crop is out the ground – giving themselves time to assess the visible weed pressure plus the impact of pests such as cabbage stem flea beetle and slugs,” he added.   

There are three treatment options available when using Belkar.

At two true leaves an application at 0.25l/ha will take out the weeds which have germinated alongside the crop and, in some circumstances, that may be enough broadleaf control before an application of Astrokerb (propyzamide + aminopyralid) or Kerb Flo 500 later on. 

In high weed pressure situations where there is a further weed have flush, crops can have a second dose at 0.25l/ha two to four weeks after the first.  

A third option to be used is to wait until six true leaves of the crop and all the weeds have emerged and apply 0.5l/ha which will take care of the weeds going in to the autumn.

The spray period for Belkar is from 1 September to the end of December.